Practice multiplication, grammar and vocabulary while you feed the world at FreeRice.com http://www.freerice.com
(Sample link) National Geographic for Kids http://www.nationalgeographic.com/kids/
Math Playground Fun math activities. Make your own practice pages.
AAA Math Great math site
World Atlas and Maps Learn about continents, oceans and countries
Map Puzzles Learn about places in the world by doing map puzzles on-line
Fractions Learn and Practice Fractions
Atoms Make your own atom
States Research All 50 States
Spelling Fun at Scholastic Spelling Fun
Punctuation and Editing Help Puntuation and Editing Help
Test Prep, Practice, Review and FUN activities by grade, subject and strand. Test Prep and Fun activities
More Math Activities at Math Is Fun Math Activities at Math is Fun
The Great Plant Escape Learn about plants and soil
NCTM Illuminations math problems Math Challenges and more
Build math and language skills. Works with Wii too Arcademic Skill Builder